Women seem to get weird after having children for some reason. I think it is difficult for them to deal with the hormonal changes. She has a point about your son being your new hobby. But it sounds like you are also aware of the importance of being with your son, by building after bedtime. It is tough when wives think that the husbands job is to make money and the wifes job is to spend it. Since she likes to spend, maybe you should send (oops, I meant ASK) HER to go to the hobby shop :-). Some men find that if they do something for their wife (watch the kid while they go out with the girls, buy them something nice, or just be espeically nice to them, like cook dinner) it helps them feel like the husband deserves something too. Other wives just take more advantage!
The control thing can be especially tough. It would be very hard to get her to believe that it is her idea you go flying and buying. If it were me, I would give up the acordian and running :-), but then I am lazy and like rock-n-roll :-). I would sit down with her and explain how important flying is to you, and that you don't mean to take anything away from her by doing it. Apparently, you make enough money to pay the bills and still support both of your hobbies, so that shouldn't be a problem. Like I said, some women are more compasionate if they feel their needs are being taken care of, and are more likely to give in to the spouses desires. Others just get more demanding. I hope yours is the former. It would be unfortunate (especially, since you have a child now) to feel the need check the expiration date on the divorce papers. I hope you can work it out!
It does appear hopeful since she still calls you "honey". If she called you a less affectionate name like "You F^@#!^& B@$+@&+, there may be another solution that would be a better option